The present invention relates to disc storage systems of the type used to store information. More specifically, the invention relates to the interface between slider and a surface of a storage disc.
Magnetic disc drives are used to store magnetically encoded information. As the magnetic disc spins, a transducing head xe2x80x9cfliesxe2x80x9d over the surface of the disc. The transducing head is used to sense magnetic fields from the disc surface during readback of information, and to generate magnetic fields which are impressed onto the surface of the disc during writing of information. As the disc spins, the transducing head is supported by an xe2x80x9cair bearingxe2x80x9d which is formed between the disc surface and an air bearing slider of the transducer head assembly. The slider body has aerodynamic properties which provide a lifting force.
It is known that improved magnetic interaction between the disc surface and the transducing head can be achieved by reducing the spacing between the head slider and the disc surface. However, as the spacing between slider and disc is reduced, it becomes critical that the fly height be accurately maintained. If the slider should dip slightly, it will touch the surface of the disc and potentially damage the surface. This is particularly problematic with magnetoresistive or magneto-optic recording heads in which contact with an asperity on the disc surface can generate an error in the readback signal.
One technique for achieving very close spacing between the transducing head and the disc surface is described in U.S. Pat. No. 5,550,691 which issued Aug. 27, 1996 to Hamilton and is entitled xe2x80x9cSIZE-INDEPENDENT, RIGID-DISK, MAGNETIC, DIGITAL-INFORMATION STORAGE SYSTEM WITH LOCALIZED READ/WRITE ENHANCEMENTS. The Hamilton reference describes a slider for contact recording in which the surface of the slider is dragged across the disc surface.
A storage device for storing information includes a disc storage medium having a disc surface. An armature is positioned over the disc surface and carries a magnetoresistive or a magneto-optic head proximate the disc surface. Transducing circuitry is coupled to the head for reading and writing information onto the disc surface. The slider is coupled to the armature near an end of the armature for carrying the head and is adapted to position the head proximate the disc surface. The slider includes an interface surface facing the disc surface having an air bearing region adapted to form an air bearing with the disc surface and having at least one contact pad extending from the air bearing region for contact recording. The air bearing provides an opposed lifting force which, when combined with the contact force on the pad, is substantially equal to the preload force.
In one aspect of the invention a sacrificial wear layer is provided on the at least one contact pad. In another aspect of the invention, the contact pad has a height which is at equilibrium with the air bearing during operation of the disc whereby the air bearing forms a shock absorbing cushion for the slider.